Patent GB-1117939-A (GB)
Title: Improved arrangement for distance measurement by reflection
IPC: G01S15/14
Filed: 1965-07-15
Abstract: 1,117,939. Echo-sounding. ATLAS-WERKE A.G. 15 July, 1965 [18 July, 1964], No. 30099/65. Heading H4D. In an echo-sounding system, a digital range indication is monitored by deriving from it an analogue indication in the form of a mark on a chart recorder displaying also the echo pulses. In the ship-borne embodiment of Fig. 1a and Fig. 1b, the stylus-carrying belt 5 of an electrochemical chart recorder, a cam-operated transmission-pulse timing switch 11, and an electromagnetic tone-wheel clock-pulse generator 29, 30, are all driven by a motor 13 whose speed may be varied according to the local speed of sound in water and is measured by a motorspeed indicator 19, 21, 22. Echo signals from a receiving transducer 3 are amplified and rectified in stages 24, 25, and recorded as a trace 8. Transmission and echo pulses are shaped respectively in circuits 39 and 42-44 and trigger a bi-stable circuit 41 controlling a gate 37 through which squared-up clock pulses 36 from the generator 29, 30 are fed to a counter 38. Allowance for the draught of the ship may be made by adjusting the instant of transmission (by adjusting switch 11) and by delaying the opening or closing of gate 37. A control pulse (from bi-stable circuit 41) which closes gate 37 also passes, after a short delay, through a gate 61 to reset counter 38 and cause an output store 56 to store the count of counter 38. Store 56 feeds a decimal number indicator 57 and a printer 58. The gate-closing pulse from circuit 41 is also passed to the chart recorder to provide a monitor recording 50 in black, the echo pulses 8 being recorded in grey. A further gating circuit (Fig. 3, not shown) may control gate 37 to prevent digital measurements of ranges other than those with a selected partial range 55-50. Store 56 may sample counter 38 output every nth sounding period (n = 1, 2, 4, 8 ...) or at fixed time intervals, rather than every sounding period, to provide a suitable data input rate for printer 58 or for a subsequent digital data processing system. In this sampling arrangement a supplementary counter 62, fed either with gate 37 opening pulses or from a timer 66, periodically opens gate 61 to write the output of counter 38 into store 56. The mean range in a number of sounding periods or in a given time interval may be indicated digitally by operation of a switch 60 whereby counter 38 is reset every nth period or after the interval determined by timer 66, the clock-pulse frequency of generator 28, 30 being reduced in proportion to the time for which counter 38 is active by means of a frequency divider 67. The smallest range in a series of soundings may be digitally indicated by introducing an additional store 69 and a comparison circuit 70, where by the output of counter 38 is transferred to store 69 (and hence to store 56) only if the range value in counter 38 is less than the value stored in store 69. Provision may be made for " bridging " missing echoes to prevent false digital indications. Digital range values, together with other data such as location co-ordinates, clock time and the ship's draught, may be fed to a digital dataprocessing system.